Hi,everyone.I'm going to tell you about a terrarium setup I'm going to build.It will have two 48" light fixtures above 5 10 gallon fish tanks.The lights will be on timers,and I'm thinking of puting seedling heat mats under the tanks.It will have fish gravel in the bottom about 1" high so the plants don't sit in the water.That way I can have humid or dry tanks as I need them.I'm going to grow neps,sundew,butterwort,cobra lily seedlings and vft leaf rootings and some live sphagnum.I'm growing this in one 10 gallon terrarium now and I'm running out of room.

don't know what temp you like to have in your tank but in my bigger terrarium (60 cm x 40 cm x 40 cm) the daytemp is about 25°C and nighttemp around 20 °C. My roomtemp is always around 20°C. The terrarium only gets heated by two fluoescent lights (60 cm).
Maybe this gives you an idea of the temperaturrange in your tank.
BTW I grow lowlandneps in it & they seem to like it....

Nico

EDIT
I forgot to mention that I speak about the colder month in Germany, in summer the temp is about 5°C higher (30°C / 25 °C).